We propose a continuation of grant support for research on human visual responses in the retina and cortex. The central goal is to get a new description of color discrimination that uses information transfer analysis. The data will yield a set of "chromaticity functions" that are based on the minimum detectable color contrast between all possible pairs of wavelengths in the visible spectrum. Psychophysical results will be compared with the results of recording the electroretinogram (ERG) and the visually evoked cortical potential (VECP). We thus propose to extend and generalize the ERG research carried out on human and pigeon eyes under grant number EY 00744.